Physiological and transcriptome analyses provide new insights into the mechanism mediating the enhanced tolerance of melatonin-treated rhododendron plants to heat stress

Rhododendron is a well-known genus consisting of commercially valuable ornamental woody plant species.Heat stress is a major environmental factor that affects rhododendron growth.Melatonin was recently reported to alleviate the effects of abiotic stress on plants.However,the role of melatonin in rhododendron plants is unknown.In this study,the effect of melatonin on rhododendron plants exposed to heat stress and the potential underlying mechanism were investigated.Analyses of morphological characteristics and chlorophyll a fluorescence indicated 200μmol L–1 was the optimal melatonin concentration for protecting rhododendron plants from heat stress.To elucidate how melatonin limits the adverse effects of high temperatures,melatonin contents,photosynthetic indices,Rubisco activity,and adenosine triphosphate(ATP)contents were analyzed at 25,35,and 40℃,respectively.Compared with the control,exogenous application of melatonin improved the melatonin contents,electron transport rate,photosystem II and I activities,Rubisco activity,and ATP contents under heat stress.The transcriptome analysis revealed many of the heat-induced differentially expressed genes were associated with the photosynthetic pathway;the expression of most of these genes was down-regulated by heat stress more in the melatonin-free plants than in the melatonin-treated plants.We identified Rh PGR5A,Rh ATPB,Rh LHCB3,and Rh Rbs A as key genes.Thus,we speculate that melatonin promotes photosynthetic electron transport,improves Calvin cycle enzyme activities,and increases ATP production.These changes lead to increased photosynthetic efficiency and CO_(2) assimilation under heat stress conditions via the regulated expression of specific genes,including Rh Rbs A.Therefore,the application of exogenous melatonin may increase the tolerance of rhododendron to heat stress.

Performances of conventional fusion methods evaluated for inland water body observation using GF-1 image

Satellite remote sensing of inland water body requires a high spatial resolution and a multiband narrow spectral resolution, which makes the fusion between panchromatic(PAN) and multi-spectral(MS) images particularly important. Taking the Daquekou section of the Qiantang River as an observation target, four conventional fusion methods widely accepted in satellite image processing, including pan sharpening(PS), principal component analysis(PCA), Gram-Schmidt(GS), and wavelet fusion(WF), are utilized to fuse MS and PAN images of GF-1.The results of subjective and objective evaluation methods application indicate that GS performs the best,followed by the PCA, the WF and the PS in the order of descending. The existence of a large area of the water body is a dominant factor impacting the fusion performance. Meanwhile, the ability of retaining spatial and spectral informations is an important factor affecting the fusion performance of different fusion methods. The fundamental difference of reflectivity information acquisition between water and land is the reason for the failure of conventional fusion methods for land observation such as the PS to be used in the presence of the large water body. It is suggested that the adoption of the conventional fusion methods in the observing water body as the main target should be taken with caution. The performances of the fusion methods need re-assessment when the large-scale water body is present in the remote sensing image or when the research aims for the water body observation.

Establishment and Verification of An Efficient Virus-induced Gene Silencing System in Forsythia

To understand the functional identification of large-scale genomic sequences in Forsythia,tobacco rattle virus(TRV)-mediated virus-induced gene silencing(VIGS),suitable for the plant,was explored in this study.The results showed that the TRV-mediated VIGS system could be successfully used in Forsythia for silencing the reporter gene FsPDS(Forsythia phytoene desaturase)using stem infiltration and leaf infiltrationmethods.All the treated plants were pruned below the injection site after 7–15 d infection;the FsPDS was silenced and typical photobleaching symptoms were observed in newly sprouted leaves at the whole-plant level.Meanwhile,this system has been successfully tested and verified through virus detection and qRT-PCR analysis.After the optimization,Forsythia magnesium chelatase subunit H(FsChlH)was silenced successfully in Forsythia using this system,resulting in yellow leaveswith decreased chlorophyll content.The system was stable,highly efficient and had greater rapidity and convenience,which made it suitable to study the function of genes related to physiological pathways such as growth and development,and metabolic regulation in Forsythia.

Genetic diversity analysis of Sinojackia microcarpa, a rare tree species endemic in China, based on simple sequence repeat markers

Although most Sinojackia species are endangered, they contribute greatly to the biodiversity of local ecosystems. Sinojackia microcarpa, an endangered species, is distributed only in three provinces of eastern China. Determining the genetic diversity of S. microcarpa provides key information for germplasm evaluation and species conservation. Here we used simple sequence repeat (SSR) markers to investigate the genetic diversity of eight natural populations of S. microcarpa. Leaf samples were collected from 144 individuals in 8 wild populations. The 156 bands were generated from 14 pairs of informative SSR primers, with an average percentage of polymorphic bands of 45.67%. The average values of Nei’s genetic diversity (He) and Shannon’s diversity index (I) were 0.1007 and 0.1658, respectively. The total genetic variation of S. microcarpa existed mainly within the eight populations, rather than among populations, and reached 86.41%. A cluster analysis showed that the eight wild populations of S. microcarpa could be classified into four groups, at a threshold of 4.0, based on an analysis of the SSR genotypes. Furthermore, there was a significant association between the phylogenetic relationships and the geographic locations of the S. microcarpa populations. In particular, populations from Fuyang, Jiande, and Lin’an in Zhejiang Province had close phylogenetic relationships and geographic distances. In addition, these three populations had the highest genetic diversity and the most individuals, suggesting that these three locations may be the S.microcarpa distribution center. This study serves as a model for studying the genetic diversity of endangered plant species.

Measuring loblolly pine crowns with drone imagery through deep learning

In modeling forest stand growth and yield,crown width,a measure for stand density,is among the parameters that allows for estimating stand timber volumes.However,accurately measuring tree crown size in the field,in particular for mature trees,is challenging.This study demonstrated a novel method of applying machine learning algorithms to aerial imagery acquired by an unmanned aerial vehicle(UAV)to identify tree crowns and their widths in two loblolly pine plantations in eastern Texas,USA.An ortho mosaic image derived from UAV-captured aerial photos was acquired for each plantation(a young stand before canopy closure,a mature stand with a closed canopy).For each site,the images were split into two subsets:one for training and one for validation purposes.Three widely used object detection methods in deep learning,the Faster region-based convolutional neural network(Faster R-CNN),You Only Look Once version 3(YOLOv3),and single shot detection(SSD),were applied to the training data,respectively.Each was used to train the model for performing crown recognition and crown extraction.Each model output was evaluated using an independent test data set.All three models were successful in detecting tree crowns with an accuracy greater than 93%,except the Faster R-CNN model that failed on the mature site.On the young site,the SSD model performed the best for crown extraction with a coefficient of determination(R^(2))of 0.92,followed by Faster R-CNN(0.88)and YOLOv3(0.62).As to the mature site,the SSD model achieved a R^(2)as high as 0.94,follow by YOLOv3(0.69).These deep leaning algorithms,in particular the SSD model,proved to be successfully in identifying tree crowns and estimating crown widths with satisfactory accuracy.For the purpose of forest inventory on loblolly pine plantations,using UAV-captured imagery paired with the SSD object detention application is a cost-effective alternative to traditional ground measurement.

Shared ecological mental model and ecological development of counties:Taking Anji as an example

This paper takes the County of Anji as an example and analyzes the ecological development system of counties based on the theory of mental model and complex ecosystem based on the theory of mental model and complex ecosystem. Anji ecological development system consists of ecological management subsystems, eco-industry subsystems, ecological environment subsystems, and ecological lives of the residents subsystems by shared ecological mental model as its foundation and motive power. These subsystems affect and promote each others, which eventually help people in Anji to achieve the goals of building a harmonious society, creating a beautiful countryside, and enjoying a happy life in overall. This study finds that a county's ecological development should emphasize the establishment, consolidation, externalization, and promotion of the shared ecological mental model, and follow the basic principles of "ecocentrism", "government-led" and "public participation".

Pig Price Fluctuations and Forecasting Model Based on Information Platform

Pork is common in people's daily life consumption,and it accounts for more than half of all meats. By collecting data information published by Bureau of Statistics and Bureau of Agriculture,this paper makes a statistical analysis of the influence of price fluctuation in the pork market on China's pork production,and finds that China's pork production shows a general trend of fluctuations due to the impact of price factors.According to the predecessors' studies on the factors influencing pig market price,combined with the actual situation of pig breeding in China,this paper uses the latest website data released by the government's public information platform to establish a forecasting model.

Observation on Flower Bud Differentiation of Crape Myrtle in Red Soil Environment

Flower bud differentiation is a key component of plant blooming biology and understanding how it works is vital for flowering regulation and plant genetic breeding,increasing the number and quality of flowering.Red soil is the most widely covered soil type in the world,and it is also the most suitable soil type for crape myrtle planting.The flower buds of crape myrtle(Lagerstroemia indica)planted in red soil were employed as experimental materials in this study,and the distinct periods of differentiation were identified using stereomicroscopy and paraffin sectioning.We optimized the steps of dehydration,transparency,embedding,sectioning and staining when employing paraffin sections.When seen under a microscope,this optimization can make the cell structure of paraffin sections obvious,the tissue structure complete,and the staining clear and natural.The flower bud differentiation process is divided into 7 periods based on anatomical observations of the external morphology and internal structure during flower bud differentiation:undifferentiated period,start of differentiation period,inflorescence differentiation period,calyx differentiation period,petal differentiation period,stamen differentiation period,and pistil differentiation period.The differentiation time is concentrated from the end of May to mid-June.Crape myrtle flower bud differentiation is a complicated process,and the specific regulatory mechanism and affecting elements need to be investigated further.

CO_(2)升高和增温没有稀释椴树叶片氮浓度却降低了叶片的光合能力

深入理解CO_(2)升高和全球变暖对植物的影响是预测植物适应性的关键。本研究以温带阔叶耐荫树种椴树(Tilia amurensis)幼苗为试验材料,研究了当前CO_(2)浓度和气温组合处理(CC)与预测的未来气候条件下CO_(2)升高和增温组合处理(FC)对植物光合驯化的影响模式。结果发现,FC处理促进了椴树地上部分的生长,降低了叶片的光合能力(最大羧化速率和最大电子传递速率),也降低了椴树光合作用生化限制中从羧化限制向电子传递限制过渡点的光合速率。FC处理没有改变叶片氮浓度,但是提高了单株叶片的含氮量和光合氮素利用效率。这些结果表明,在椴树适应未来气候条件中发挥重要的作用的可能是叶片的氮素利用效率,而非其光合能力。本研究为理解椴树的光合驯化特征提供了新的见解,研究结果也可以用于预测椴树在未来气候条件下可能的表现。

Removal of antibiotic-resistant genes during drinking water treatment:A review

Once contaminate the drinking water source,antibiotic resistance genes(ARGs)will propagate in drinking water systems and pose a serious risk to human health.Therefore,the drinking water treatment processes(DWTPs)are critical to manage the risks posed by ARGs.This study summarizes the prevalence of ARGs in raw water sources and treated drinking water worldwide.In addition,the removal efficiency of ARGs and related mechanisms by different DWTPs are reviewed.Abiotic and biotic factors that affect ARGs elimination are also discussed.The data on presence of ARGs in drinking water help come to the conclusion that ARGs pollution is prevalent and deserves a high priority.Generally,DWTPs indeed achieve ARGs removal,but some biological treatment processes such as biological activated carbon filtration may promote antibiotic resistance due to the enrichment of ARGs in the biofilm.The finding that disinfection and membrane filtration are superior to other DWTPs adds weight to the advice that DWTPs should adopt multiple disinfection barriers,as well as keep sufficient chlorine residuals to inhibit re-growth of ARGs during subsequent distribution.Mechanistically,DWTPs obtain direct and inderect ARGs reduction through DNA damage and interception of host bacterias of ARGs.Thus,escaping of intracellular ARGs to extracellular environment,induced by DWTPs,should be advoided.This review provides the theoretical support for developping efficient reduction technologies of ARGs.Future study should focus on ARGs controlling in terms of transmissibility or persistence through DWTPs due to their biological related nature and ubiquitous presence of biofilm in the treatment unit.